1. Field of the Invention
The present invention relates to an additional information transmission method for transmitting not only an information signal such as a video signal but also additional information on this information signal, an additional information transmission system, an information signal output apparatus used in this system, an information signal processing apparatus, an information signal recording apparatus and an information signal recording medium.
2. Description of the Related Art
Various contents information such as image information or voice information has been abundantly provided through a video tape, a digital video disk (DVD), internet or broadcasting media. On the other hand, the piracy problem due to the illegal duplication (copy) of such various contents information which have been provided through various media is emerging.
To cope with this problem, various measures are taken, which measures include, for example, adding information for duplication control or copyright information to contents information such as image information to prevent illegal duplication of the contents information and tracking parties involved in the illegal duplication of contents information.
There is also proposed a method of superimposing additional information added to the contents information by means of electronic watermark processing. This electronic watermark processing is to embed information as noise into portions which exist on image data or music data and which are not important for human perception, i.e., portions which are not redundant to music and pictures.
The additional information embedded into the image data or music data by means of such electronic watermark processing is difficult to remove from the image data or music data. Even after the image data or music data has been subjected to filtering or data compression processing, the electronic watermark added information (electronic watermark information) embedded thereinto can be extracted from the image data or music data.
By using the electronic watermark processing as stated above, it is possible to superimpose electronic watermark information on contents information so that the information cannot be easily removed or manipulated and to extract the electronic watermark information superimposed on the contents information at, for example, a recording apparatus. Thus, using the electronic watermark information superimposed on the contents information, the illegal duplication of the content information is prevented and the like.
In the meantime, one of the electronic watermark processings is to use a spectrum spread technique. This is intended to spectrum-spread additional information to turn the information into a low level, wide bandwidth signal so that it can be regarded as noise with respect to an information signal of, for example, a video signal, and to superimpose the additional information on the information signal such as a video signal.
The spectrum spreading of additional information is carried out by multiplying the additional information by a spread code which is generated in a sufficiently short cycle. If spectrum-spreading the additional information, the additional information, which is turned into a low level, wide bandwidth signal, can be extracted as an original high level, narrow bandwidth signal by conducting de-spread for multiplying it with the same spread code as that in spectrum spread at the same timing as that of spectrum spread.
Due to this, the following are proposed. If a spectrum spread signal which is spectrum-spread additional information is superimposed on a video signal, a spread code is generated to be synchronous with a vertical synchronizing signal in, for example, a one-frame cycle or two-frame cycle. Using the spread code, the spectrum-spread additional information is superimposed on the video signal.
By doing so, if the spectrum spread signal superimposed on the vide signal is extracted, the spectrum-spread additional information superimposed on the vide signal can be de-spread by generating the same spread code as that during spectrum spread at the same time while using a vertical synchronizing signal as a reference signal. Thus, it is possible to promptly and accurately extract the spectrum-spread additional information superimposed on the video signal.
Further, even if the additional information on the video signal is superimposed on the video signal with a spectrum spread signal and transmitted as stated above, it is considered that a state in which the spectrum-spread signal is superimposed on the video signal or the content of the additional information transmitted by the spectrum spread signal is illegally detected by various methods.
In that case, there is a fear that the removal or manipulation of the spectrum spread signal superimposed on the video signal is easily made based on the illegally detected information. This may possibly occur not only to a case where additional information is superimposed as a spectrum spread signal on a video signal but also to a case where additional information is superimposed as electronic watermark information on various information signals such as a voice signal and computer data and then transmitted.
Due to this, it is desired that the strength of the additional information superimposed as a spectrum spread signal on the information signal such as a video signal, is intensified against illegal attempts to thereby make it possible to surely, accurately provide the other side with the additional information on the video signal together with the video signal.
Further, a demand for superimposing not only information for duplication control (duplication control information) but also further additional information such as copyright information on the transmitted information signal on the information signal and transmitting them. That is, there is a demand for superimposing both duplication control information serving as additional information and further additional information on an information signal and transmitting the both information.
In this case, it is required to make the additional information difficult to remove or manipulate, to ensure providing the information signal to the side supplied with the information signal and to allow the side supplied with the information signal to surely and accurately detect further additional information provided after being superimposed on the information signal.
Nevertheless, it is difficult to ensure transmitting duplication control information and further additional information and to detect these pieces of information separately from each other only by superimposing further additional information in addition to the duplication control information both serving as electronic watermark information on an information signal such as a video signal.
In view of the above, an object of the present invention is to provide an additional information transmission method for making higher the concealment characteristics of additional information transmitted as electronic watermark information together with an information signal and for surely, accurately transmitting the additional information, an additional information transmission system using this method, an information signal output apparatus used in this system, an information signal processing apparatus, an information signal recording apparatus and an information signal recording medium.
Further, another object of the present invention is to provide an additional information transmission method, an additional information transmission system as well as an information signal output apparatus and an information signal processing apparatus used in the system which can superimpose a plurality of types of additional information on an information signal using electronic watermark information to surely provide the information to a receiving side and which allows the side supplied with the information signal to surely and accurately detect each of the plural additional information superimposed on the information signal.
To solve the above problems, an additional information transmission method recited in claim 1 is characterized in that the method comprises transmitting additional information on an information signal by a superimposition/non-superimposition pattern consisting of a preset combination of a block in which electronic watermark information is superimposed on the information signal and the block in which the electronic watermark information is not superimposed on the information signal.
According to the additional information transmission method recited in claim 1, the additional information on the information signal is transmitted by the superimposition/non-superimposition pattern of the electronic watermark information superimposed on the information signal.
In this way, since the additional information is transmitted while utilizing the superimposition/non-superimposition pattern of the electronic watermark information, the side supplied with the information signal on which the electronic watermark information is superimposed detects the superimposition/non-superimposition pattern of the electronic watermark information superimposed on the information signal, thereby making it possible to surely detect the additional information.
Further, the content of the additional information cannot be known by simply detecting the electronic watermark information. It is required to detect the superimposition/non-superimposition pattern of the electronic watermark information and discriminate additional information corresponding to the superimposition/non-superimposition pattern. Due to this, it is possible to transmit the additional information more surely without the leakage of the additional information during transmission or the like and it is, therefore, possible to enhance the reliability of the additional information.
Moreover, if the additional information superimposed on the information signal is to be removed or manipulated, it is required to remove or manipulate the entire superimposition/non-superimposition of the electronic watermark information. This can make it more difficult to remove or manipulate the additional information superimposed on the information signal. Also, the additional information superimposed on the information signal cannot be completely removed or manipulated only by removing or manipulating part of the superimposition/non-superimposition pattern of the electronic watermark information. Thus, the strength of the additional information superimposed on the information signal can be intensified and the reliability of the additional information can be thereby enhanced.
Further, an additional information transmission method recited in claim 2 is the additional information transmission method according to claim 1 and characterized in that a plurality of the superimposition/non-superimposition patterns are set to correspond to a plurality of additional information, respectively; and
the method comprises detecting a superimposition/non-superimposition pattern of the electronic watermark information superimposed on the information signal transmitted, and discriminating corresponding additional information from among the plurality of additional information based on the superimposition/non-superimposition pattern.
According to the additional information transmission method recited in claim 2, there are a plurality of additional information on the information signal to be transmitted together with the information signal and a plurality of superimposition/non-superimposition patterns corresponding to the plural additional information are preset. Then, based on the superimposition/non-superimposition patterns of the additional information transmitted together with the information signal, the electronic watermark information is superimposed on the information signal.
By doing so, it is possible to surely transmit all of the plurality of additional information on the information signal by the superimposition/non-superimposition patters of the plural electronic watermark information.
Also, an additional information transmission method recited in claim 3 is the additional information transmission method according to claim 1 or 2, and is characterized in that the information signal is a video signal, the block in which the electronic watermark information is superimposed or not superimposed is set as a block synchronous with a video synchronizing signal, and the electronic watermark information is a spectrum spread signal formed by using a spread code generated synchronously with the video synchronizing signal.
According to the additional information transmission method recited in claim 3, the spectrum spread signal serving as electronic watermark information is formed by using the spread code generated synchronously with the video synchronizing signal, the block in which the spectrum spread signal is superimposed or not superimposed is set as a block synchronous with the video synchronizing signal such as one block consisting of one frame or one block consisting of two frames.
This makes it possible to transmit the additional information by superimposing it on the information signal by the superimposition/non-superimposition pattern of the electronic watermark information. The side supplied with the video signal on which the additional information is superimposed generates a de-spread spread code using the video synchronizing signal of the supplied video signal as a reference signal, thereby making it possible to promptly and accurately detect the superimposition/non-superimposition pattern of the spectrum spread signal superimposed on the video signal and to promptly and accurately detect the additional information corresponding to the superimposition/non-superimposition pattern.
In addition, an additional information transmission method recited in claim 4 is the additional information transmission method according to claim 1, and is characterized in that synchronism detection electronic watermark information for detecting a superimposition/non-superimposition pattern of the electronic watermark information superimposed on the information signal, is superimposed on the information signal between one the superimposition/non-superimposition pattern and another the superimposition/non-superimposition pattern or in the forefront of the superimposition/non-superimposition pattern.
According to the additional information transmission method recited in claim 4, it is possible to surely match synchronism when detecting the superimposition/non-superimposition pattern of the electronic watermark information by detecting synchronism detection electronic watermark information.
For example, even if the superimposition/non-superimposition pattern of electronic watermark information is superimposed on an information signal, such as a voice signal or computer data transmitted between computers, which does not have a synchronizing signal unlike a video signal, it is possible to ensure detecting the superimposition/non-superimposition pattern of the electronic watermark information and ensure discriminating the additional information corresponding to the superimposition/non-superimposition pattern.
Moreover, an additional information transmission method recited in claim 5 is the additional information transmission method according to claim 4, and is characterized in that the electronic watermark information for forming the superimposition/non-superimposition pattern and the synchronism detection electronic watermark information are spectrum spread signals formed by using different spread codes.
According to the additional information transmission method recited in claim 5, the electronic watermark information for forming a superimposition/non-superimposition pattern and the synchronism detection electronic watermark information are formed by using different spread codes. Due to this, it is possible to surely detect both of the information without taking one for another.
As a result, it is possible to surely transmit the additional information by the superimposition/non-superimposition pattern of the electronic watermark information to the other side and to cause the other side to detect synchronism detection electronic watermark information and to thereby match synchronizing timing, surely and accurately detect the superimposition/non-superimposition pattern of the electronic watermark information and discriminate the additional information superimposed on the transmitted information signal.
Furthermore, an additional information transmission method recited in claim 6 is the additional information transmission method according to claim 1 or 2, and is characterized in that the electronic watermark information for forming the superimposition/non-superimposition pattern and synchronism detection electronic watermark information for detecting the superimposition/non-superimposition pattern of the electronic watermark information superimposed on the information signal are formed for the information signal by using different spread codes and are superimposed on the information signal in the same time range of the information signal.
According to the additional information transmission method recited in claim 6, the electronic watermark information for forming a superimposition/non-superimposition pattern and the synchronism detection electronic watermark information are formed by using different spread codes. owing to this, even if the both information are superimposed on the information signal in the same time range, they can be surely detected, individually.
As a result, by surely transmitting the additional information by the superimposition/non-superimposition pattern of the electronic watermark information to the other side and causing the other side to detect the synchronism detection electronic watermark information, it is possible to match synchronizing timing, to surely and accurately detect the superimposition/non-superimposition pattern of the electronic watermark information and to discriminate the additional information superimposed on the transmitted information signal.
It is noted that it is also possible to transmit additional information by the reversal/non-reversal pattern of the electronic watermark information between the block in which the electronic watermark information is superimposed as it is and that in which the electronic watermark information is superimposed with its phase reversed instead of transmitting the additional information by the superimposition/non-superimposition pattern of the electronic watermark information.
In this way, if a block in which the electronic watermark information is superimposed on the video signal as it is and a block in which the electronic watermark information is superimposed with its phase reversed are generated, it is possible to make the difference in the level of the electronic watermark information larger between the block in which the electronic watermark information is superimposed as it is and that in which the electronic watermark information is superimposed with its phase reversed.
Thus, it is possible to decrease the influence of the information signal on the electronic watermark information superimposed on the information signal and to thereby surely transmit and detect the electronic watermark information. Besides, in that case, the block in which the electronic watermark information is not superimposed is not used, so that it is possible to intensify the strength of the electronic watermark information against illegal attempts such as the removal or manipulation of the electronic watermark information.